Chelsea have postponed the surgery needed by Alex to ensure the centre-half is available for selection for this afternoon's potentially awkward match at Birmingham City as they seek to steer a passage through their defensive crisis.

Alex requires an arthroscopic procedure on his right knee, badly swollen after the recent loss to Liverpool, which will sideline the 28-year-old for up to eight weeks. The champions had intended the centre-half to undergo surgery this week but Alex, having trained and sat on the bench with Brazil for their game with Argentina in Qatar on Wednesday, has declared himself fit to feature at St Andrew's, where his presence is much needed against the likes of Nikola Zigic given the continued absence of John Terry.

Alex said he would play "to help the team", though he admitted he will not be fully fit and envisages returning to Brazil for surgery on Thursday. "There is no risk putting him in," said Carlo Ancelotti, the manager. "He'll have the surgery next week, after this game, though if he feels good and the knee is still OK, we can still postpone it. It wouldn't cause any more damage to do that. He trained for two days with the Brazilian team, then sat on the bench for the game, and the knee was OK. I had the same problem 20 years ago and postponed my surgery for two months. Sometimes I had pain, and swelling, but I was still able to play."

There was relatively optimistic news, too, on Terry, who visited Dr Jean-Pierre Meersseman, a Belgian chiropractor at Milan since 1988 with whom Ancelotti has worked in the past, in midweek and will do again after the weekend. Physiotherapy is ongoing to relax the piriformis muscle, which is irritating Terry's sciatic nerve, on a daily basis with Chelsea optimistic their captain will not, as feared, be absent for months. They apparently retain some hope that he could feature at Newcastle next weekend.

"There was good news from the visit to Italy and they've identified they have to relax that muscle so that the nerve is not touched," said Ancelotti. "It depends day by day. He's disappointed, but he's also optimistic and in a good frame of mind. Every day he's coming in earlier for treatment, which is good." Asked whether he would attempt to add to his defensive options in the January transfer window, said: "It depends what happens with Alex and, in the next days, with Terry. Obviously, if both players are not able to play for a long time, we will have to think about this. But only if that is the case."

While there is relief at Alex's return – Paulo Ferreira and Branislav Ivanovic's makeshift pairing had been badly exposed by Sunderland last Sunday – there remains some level of surprise at the implications of Michael Emenalo's appointment as assistant first-team coach to succeed the sacked Ray Wilkins. The Nigerian had been working as head opposition scout and will effectively continue in that role while he updates his coaching qualifications. Ancelotti was keen to point out that, despite Emenalo's promotion, there would be no change to the day-to-day workings of his backroom staff.

The Italian made it clear that this was the club's appointment and suggested Emenalo may not be used as a conventional coach when he has qualified. "The club made this decision after the decision on Ray, but nothing has changed for me," he said. "Emenalo has been our opposition scout and has been supporting me since I've been here. He's not been involved in the training and won't be now because [another of the assistant first-team coaches] Paul Clement does that. I'm not here to explain how I feel at this moment. I'm a professional. I will continue to work and want to stay focused on my team.

"Emenalo has fantastic experience because he has seen a lot of games of the opposition, so he's tactically strong and has good knowledge. He will continue to do the same. I will maintain the same relationship with him as I did before Ray left. But I am not thinking about this. We don't want to bury our heads in the sand. This is an important game and we can either move on from the [Sunderland] defeat or we can stay in a difficult moment. It all depends on us."